To be honest, I've never gotten along with any multi-finder I've tried so far. I do have a VIDOM (earlier version of the VIOOH, essentially) and also a TEWE multi-finder that covers 35 - 180mm. Unfortunately, I have no experience with any Nikon finders.
The Leica VIDOM has a L/R reversed image so you have to deal with that. (The VIOOH does not have this issue, I believe). Both are cropping type finders, that is, they simply reduce the viewing window size as you rotate their control. And there's no "eye relief" to speak of... I practically have to stick the viewing eyepiece end into my eyeball. Not great...
The TEWE is the type that telescopes and magnifies the image - keeping the viewfinder image more or less the same size. This is better, I think. And, for its size it's not too heavy. But all of these multi-finders are pretty huge compared to the size of our little Leica bodies. This fact may or may not bother you.
In the end I just decided to use a variety of the single viewfinders such as the SBOOI (50mm), SBLOO (35mm), etc. I rarely, if ever, feel the need to have one finder that covers every conceivable focal length. For example, on a typical hike I'll probably have just two lenses (50 and 135) and one body. In that case, I'd have the 135 brightline finder mounted on the camera top and just use the built-in VF for 50mm. (I have a SBOOI also, but I really don't mind using the camera's VF).
The TEWE finders show up on ebay very often so you can see how they compare, physically, with the Leica pieces.